Process monitoring system, process monitoring method, and method for manufacturing semiconductor device

ABSTRACT

A process monitoring system has a process chamber configured to hold an object to be processed, an illumination source configured to emit a light to the object, a polarizer configured to polarize the light, a monitor window having a birefringent material and provided on the process chamber to propagate the light, direction adjusting equipment configured to adjust a relationship between a polarization plane of the light and a direction of an optic axis of the monitor window, and a monitoring information processor configured to detect the light reflected from the object.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority fromprior Japanese Patent Application P2003-362134 filed on Oct. 22, 2003;the entire contents of which are incorporated by reference herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to measurement techniques and inparticular to a process monitoring system, a process monitoring method,and a method for manufacturing a semiconductor device.

2. Description of the Related Art

In semiconductor manufacturing process, a depth of an etched groove anda thickness of a deposited membrane are controlled by monitoring anetching time and a deposition time. However, such monitoring methodcannot operate precisely when a process environment, such as temperatureand pressure, is changed unexpectedly. The imprecise monitoringdecreases the yield rate of the manufactured semiconductor devices.Therefore, process monitoring systems measuring the actual depth of theetched groove or the actual thickness of the deposited membrane has beenrecently introduced.

In Japanese Patent Laid-Open Publication No. 2002-93870, a processmonitoring system is disclosed, in which an inspection light isirradiated on an object to be processed. The object is held in a processchamber. The light is irradiated through a monitor window provided inthe process monitor. The disclosed system estimates the actual depth ofthe etched groove or the actual thickness of the deposited membrane onthe object to be processed by detecting the reflected inspection light.

However, if the monitor window is composed of birefringent material andthe inspection light is polarized, the monitor window interacts with theinspection light and modulates the phase of the light. Such phenomenoncauses interference noises in a spectrum of the inspection light.Therefore, it is difficult to achieve a precise monitoring.

Also, an upper electrode is provided in the process chamber of plasmaprocess. A plurality of nozzle holes is formed in the upper electrode inorder to supply an interior of the process chamber with a reaction gas.However, if the monitor window is provided on the upper electrode, themonitor window disturbs a stable supply of the reaction gas since themonitor window does not include the nozzle holes. Therefore, thereaction gas concentration beneath the monitor window becomes less thanin other space. Consequently, the evenness of an etching rate ordeposition rate in the process chamber is decreased.

SUMMARY OF THE INVENTION

An aspect of present invention inheres in a process monitoring systemaccording to an embodiment of the present invention. The system includesa process chamber configured to hold an object to be processed, anillumination source configured to emit a light to the object, apolarizer configured to polarize the light, a monitor window having abirefringent material and provided on the process chamber to propagatethe light, direction adjusting equipment configured to adjust arelationship between a polarization plane of the light and a directionof an optic axis of the monitor window, and a monitoring informationprocessor configured to detect the light reflected from the object.

Another aspect of the present invention inheres in a process monitoringsystem according to the embodiment of the present invention. The systemincludes a process chamber configured to hold an object to be processed,an illumination source configured to emit a light to the object, amonitor window provided on the process chamber to propagate the light,the monitor window having a plurality of nozzle holes, the diameter ofthe nozzle holes being smaller than a beam diameter of the light in themonitor window, and a monitoring information processor configured todetect the light reflected from the object.

Yet another aspect of the present invention inheres in a processmonitoring method according to the embodiment of the present invention.The method includes i inserting an object to be processed into a processchamber, the process chamber having a monitor window containing abirefringent material, irradiating a light to the object through themonitor window, polarizing the light, adjusting a relationship between apolarization plane of the light and a direction of an optic axis of themonitor window, and detecting the light reflected from the object.

Yet another aspect of the present invention inheres in a processmonitoring method according to the embodiment of the present invention.The method includes inserting an object to be processed into a processchamber, the process chamber having a monitor window, irradiating alight to the object through the monitor window, focusing the light sothat a beam diameter of the light in the monitor window is larger thaneach diameter of a plurality of nozzles hole formed in the monitorwindow, and detecting the light reflected from the object.

Yet another aspect of the present invention inheres in a method formanufacturing a semiconductor device according to the embodiment of thepresent invention. The manufacturing method includes forming aninsulating film above a semiconductor substrate, arranging an etchingmask on the insulating film, inserting the semiconductor substrate intoa process chamber, the process chamber having a monitor windowcontaining a birefringent material, irradiating a polarized light to asurface of the semiconductor substrate through the monitor window,adjusting a relationship between a polarization plane of the light and adirection of an optic axis of the monitor window, etching the insulatingfilm in the process chamber, monitoring an end point of the etching bydetecting the light reflected from the semiconductor substrate havingthe insulating film thereabove, and stopping the etching.

Yet another aspect of the present invention inheres in a method formanufacturing a semiconductor device according to the embodiment of thepresent invention. The manufacturing method includes forming aninsulating film above a semiconductor substrate, arranging an etchingmask on the insulating film, inserting the semiconductor substrate intoa process chamber, the process chamber having a monitor window, focusinga light so that a beam diameter of the light in the monitor window islarger than each diameter of a plurality of nozzle holes formed in themonitor window, supplying a reaction gas into the process chamberthrough the nozzle holes, etching the insulating film in the processchamber, monitoring an end point of the etching by detecting the lightreflected from the semiconductor substrate having the insulating filmthereabove, and stopping the etching.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram of a process monitoring system of plasma process inaccordance with a first embodiment of the present invention;

FIG. 2 is a sectional view of a measuring object in accordance with thefirst embodiment of the present invention;

FIG. 3 is a plan view of the measuring object in accordance with thefirst embodiment of the present invention;

FIG. 4 is a first exploded perspective view of a polarizer and a monitorwindow in an optical system in accordance with the first embodiment ofthe present invention;

FIG. 5 is a second exploded perspective view of the polarizer and themonitor window in the optical system in accordance with the firstembodiment of the present invention;

FIG. 6 is a third exploded perspective view of the polarizer and themonitor window in the optical system in accordance with the firstembodiment of the present invention;

FIG. 7 is a sample graph of a spectrum of an inspection light inaccordance with the first embodiment of the present invention;

FIG. 8 is a fourth exploded perspective view of the polarizer and themonitor window in the optical system in accordance with the firstembodiment of the present invention;

FIG. 9 is a flowchart depicting a process monitoring method inaccordance with the first embodiment of the present invention;

FIG. 10 is a flowchart depicting a method for manufacturing asemiconductor device in accordance with the first embodiment of thepresent invention;

FIG. 11 is a first sectional view of the semiconductor device depictingthe manufacturing process in accordance with the first embodiment of thepresent invention;

FIG. 12 is a second sectional view of the semiconductor device depictingthe manufacturing process in accordance with the first embodiment of thepresent invention;

FIG. 13 is a plan view of the semiconductor device depicting themanufacturing process in accordance with the first embodiment of thepresent invention;

FIG. 14 is a third sectional view of the semiconductor device depictingthe manufacturing process in accordance with the first embodiment of thepresent invention;

FIG. 15 is a diagram of a dry process apparatus in accordance with asecond embodiment of the present invention;

FIG. 16 is an exploded perspective view of a monitor window inaccordance with the second embodiment of the present invention;

FIG. 17 is a flowchart depicting a process monitoring method inaccordance with the second embodiment of the present invention; and

FIG. 18 is a flowchart depicting a method for manufacturing asemiconductor device in accordance with the second embodiment of thepresent invention.

DETAILED DESCRIPTION OF THE INVENTION

Various embodiments of the present invention will be described withreference to the accompanying drawings. It is to be noted that the sameor similar reference numerals are applied to the same or similar partsand elements throughout the drawings, and the description of the same orsimilar parts and elements will be omitted or simplified.

First Embodiment

With reference to FIG. 1, a process monitoring system 10 of plasmaprocess according to a first embodiment of the present invention has aprocess chamber 50 of plasma process configured to hold an object 16 tobe processed, an illumination source 12 configured to emit an inspectionlight hγ_(i) to the object 16, a polarizer 60 configured to polarize theinspection light hγ_(i), a monitor window 54 containing a birefringentmaterial and provided on the process chamber 50 of the plasma process topropagate the inspection light hγ_(i), direction adjusting equipment 7configured to adjust a relationship between a polarization plane “P” ofthe inspection light hγ_(i) and a direction of an optic axis “A” of themonitor window 54, and a monitoring information processor 28 configuredto detect reflected inspection light hγ_(i) reflected from the object16, which is to be processed.

The inspection light hγ_(i) emitted from the illumination source 12 ispropagated through an optical fiber 20 a. Spatial noise of theinspection light hγ_(i) is eliminated by a spatial filter 62. Theinspection light hγ_(i) propagates through a beam splitter 18 and iscondensed by a lens 14.

The oscillation of the linearly polarized inspection light hγ_(i) isconfined to a polarization direction “E” perpendicular to thepropagation direction by the polarizer 60. A rotator 5 is configured torotate the polarizer 60 to define the polarization direction “E” of theoscillation.

The monitor window 54 is provided in an upper portion of the processchamber 50 of the plasma process. A direction adjuster 6 is attached tothe monitor window 54. The direction adjuster 6 is configured to adjustthe optic axis “A” direction of the monitor window 54. The details ofthe optic axis “A” will be described below. A z-axis goniometer and arotation stage may be used for the direction adjuster 6. The directionadjuster 6 and the rotator 5 implement a direction adjusting equipment7.

A substrate holder 15 is disposed in the process chamber 50 of theplasma process. The substrate holder 15 is configured to hold the object16. The inspection light hγ_(i) is focused on the surface of the object16 through the monitor window 54. A turntable that can rotate the object16 is available as the substrate holder 15. Therefore, it is possible toadjust the relationship between the polarization direction “E” of theoscillation of the inspection light hγ_(i) and an orientation of thedisposed object 16 with the direction adjusting equipment 7 and thesubstrate holder 15.

A reflected light hγ_(r) from the surface of the object 16 to beprocessed is transmitted to the monitoring information processor 28through the monitor window 54, the polarizer 60, the lens 14, the beamsplitter 18, and an optical fiber 20 b.

The monitoring information processor 28 analyzes a reflection lighthγ_(r) of the inspection light hγ_(i). The monitoring informationprocessor 28 has a spectroscope 22, a detector 24, and a calculator 26.The spectroscope 22 observes a spectrum of the reflected light hγ_(r).The detector 24 detects the light intensity of the reflected lighthγ_(r) at each wavelength. The calculator 26 calculates information onthe thickness direction of the object 16 from the light intensity.Information about the thickness of a thin film and the depth of anetched groove is an example of the “information on the thicknessdirection of the object 16”.

An example of the object 16 is shown in FIG. 2. The object 16, to beprocessed, has a semiconductor substrate 80, a first insulating film 81disposed on the semiconductor substrate 80, a first circuit layer 82disposed on the first insulating film 81, second insulating film 83disposed on the first circuit layer 82, and a plurality of resist masks85 a, 85 b, 85 c, 85 d, 85 e, 85 f disposed on the second insulatingfilm 83. The plurality of resist masks 85 a-85 f are arranged inparallel with a direction “D₁” as shown in FIG. 3. In the first circuitlayer 82, a plurality of wires 82 a, 82 b, 82 c, 82 d, 82 e are arrangedin parallel with a direction “D₂”. The direction “D₂” is perpendicularto the direction “D₁”.

With reference again to FIG. 1, the rotator 5 and the polarizer 60confines the polarization direction “E” of the oscillation of theinspection light hγ_(i) to the direction “D₂” shown in FIG. 3. In thiscase, the inspection light hγ_(i) cannot penetrate the first circuitlayer 82 and is reflected from the first circuit layer 82. Therefore, itis possible to eliminate the influence on the inspection light hγ_(i)caused by layers beneath the first circuit layer 82.

With reference next to FIG. 4 and FIG. 5, the optical relationshipbetween the polarizer 60 and the monitor window 54 is depicted. Themonitor window 54 is composed of a birefringent crystal such assapphire, quarts, and calcite. In the birefringent crystal, there is onedirection such that any light, regardless of the state of polarizationof the light, has the same speed in that direction. Such direction iscalled the “optic axis”. The direction adjuster 6 shown in FIG. 1adjusts relative relationship between a polarization plane “P” of theinspection light hγ_(i) and the direction of the optic axis “A”. In FIG.4, the monitor window 54 is oriented so that the optic axis “A” issubstantially parallel with the polarization plane “P”. In FIG. 5, aperpendicular plane “X” is substantially parallel to the propagation ofthe inspection light hγ_(i) and is perpendicular to the polarizationplane “P”. Here, the monitor window 54 is oriented so that the opticaxis “A” is substantially parallel with the perpendicular plane “X”.

With reference next to FIG. 6, the monitor window 54 is oriented so thatthe optic axis “A” is substantially parallel with a plane “B” crossingthe polarization plane “P” at an angle of 45 degree.

FIG. 7 shows an example spectrum detected by the detector 24 shown inFIG. 1. As shown in FIG. 7, sawtooth pulses appear in the spectrum whenthe monitor window 54 is oriented so that the optic axis “A” issubstantially parallel with the plane “B” crossing the polarizationplane “P” at an angle of 45 degree as shown in FIG. 6. This is becausethe monitor window 54 composed of birefringent crystal interacts withthe inspection light hγ_(i) and modulates the phase of the light.

On the other hand, the sawtooth pulses disappear when the monitor window54 is oriented so that the optic axis “A” is substantially parallel withthe polarization plane “PI” (0 degree) as shown in FIG. 4 or the opticaxis “A” is substantially parallel with the polarization plane “P” (90degree) as shown in FIG. 5.

It should be noted that it is permissible for the direction of the opticaxis “A” shown in FIG. 4 to be slightly different from the paralleldirection of the polarization direction “E”. Also, it is permissible forthe direction of the optic axis “A” shown in FIG. 5 to be slightlydifferent from the parallel direction of the perpendicular plane “X”. Ifthe differences are less than ii degree, the sawtooth pulses areeffectively eliminated.

It is also possible to eliminate the sawtooth pulses with the monitorwindow 54 having the optic axis “A” substantially parallel with thepropagation of the inspection light hγ_(i) as shown in FIG. 8. Theslight difference, such as ii degree, between the direction of the opticaxis “A” and the propagation of the inspection light hγ_(i) ispermissible. In this case, the rotator 5 in the direction adjustingequipment 7 configured to adjust the orientation of the polarizer 60 maybe solely controlled.

By adjusting the direction of the optic axis “A” in the monitor window54 as shown in FIGS. 4,5 and 8, the process monitoring system 10 makesit possible to eliminate the sawtooth pulses from the inspection lighthγ_(i) spectrum. In an earlier process monitoring system, the opticalrelationship between the polarizer and the monitor window composed ofbirefringent crystal was not important. Therefore, the sawtooth pulsesappeared in the spectrum affected precise measurement. However, theprocess monitoring system 10 makes it possible to obtain preciseinformation on the thickness direction of the object 16. Therefore, theprocess monitoring system 10 makes it possible to monitor themanufacturing process of fine and precise semiconductor devices.

With reference next to FIG. 9, a process monitoring method according tothe first embodiment of the present invention is described.

In step S101, the object 16 such as the semiconductor substrate 80covered with the second insulating film 83 and the resist masks 85 a-85f shown in FIGS. 2 and 3 is disposed on the substrate holder 15 in theprocess chamber 50 of the plasma process.

In step S102, the illumination source 12 emits the inspection lighthγ_(i). The inspection light hγ_(i) is propagated through the spatialfilter 62, beam splitter 18, lens 14, polarizer 60, and the monitorwindow 54. Consequently, the object 16 is exposed to the inspectionlight hγ_(i).

In step S103, the polarizer 60 shown in FIG. 1 is rotated by the rotator5 so that the polarization direction “E” of the inspection light hγ_(i)and the direction “D₂” shown in FIG. 3 are equivalent. Rotating thepolarizer 60 by hand is an alternative.

In step S104, the direction adjuster 6 adjusts the orientation of themonitor window 54 in order to optimize the relationship between thepolarization direction “E” of the linearly polarized inspection lighthγ_(i) and the optic axis “A” of the monitor window 5 as shown in FIGS.4 and 5.

In step S105, the monitoring information processor 28 detects thereflected light hγ_(r) propagated through the monitor window 54, thepolarizer 60, the lens 14, the beam splitter 18, and the light fiber 20b. Thereafter, the monitoring information processor 28 analyzes thereflected light hγ_(r) and calculates the thickness direction of thesecond insulating film 83 shown in FIGS. 2 and 3, based on theinformation received via the reflected light hγ_(r).

Process monitoring methods of earlier technology generate the noises asthe sawtooth pulses in the light spectrum. Such noise caused by thebirefringence prevent precise measuring of the information on thethickness direction. However, the process monitoring method according tothe first embodiment makes it possible to calculate accurate informationon the thickness direction since the relationship between thepolarization direction “E” and the optic axis A is optimized in stepS104 in order to eliminate such noise.

With reference next to FIG. 10, a method for manufacturing thesemiconductor device according to the first embodiment of the presentinvention is described.

With reference to FIG. 11, boron is implanted into a semiconductorsubstrate 1 such as an n-type Si wafer in step S201. The semiconductorsubstrate 1 is then heated to diffuse the implanted boron and a p-well302 is formed. The semiconductor substrate 1 is selectively etched andtrenches 303, 403 are delineated. Thereafter, an isolation insulator 304is deposited into the trenches 303, 403 by chemical vapor deposition(CVD). The semiconductor substrate 1 is oxidized to form a gate oxidefilm 305. A poly silicon gate 307 is deposited on the gate oxide film305 by the CVD method and etching is performed. Then, self-alignedsource/drain regions 310, 311 are formed by phosphorous ion implantationand annealing. Subsequently, an insulating film 400 is deposited by theCVD method.

In step S202, etch masks 900, 901, 902 shown in FIGS. 12 and 13 arearranged on the insulating film 400 by lithography. In step S203, thesemiconductor substrate 1 is inserted into the process chamber 50 of theplasma process shown in FIG. 1.

In step S204, the insulating film 400 is exposed to the polarizedinspection light hγ_(i). In step S205, the orientation of the monitorwindow 54 is adjusted by the direction adjuster 6 in order to optimizethe relationship between the polarization direction “E” of the linearlypolarized inspection light hγ_(i) and the optic axis “A” of the monitorwindow 5 as shown in FIGS. 4 and 5.

In step S206, a reaction gas is introduced into the process chamber 50of the plasma process after the pressure in the process chamber 50 ofthe plasma process is reduced. With AC power in the radio frequency (RF)range, a plasma glow discharge is generated to excite a reaction nearthe exposed surface of the insulating film 400. Consequently, theexposed portions of the insulating film 400 are selectively etched so asto form damascene grooves 800, 801.

In step S207, the reflected light hγ_(r) is propagated through themonitor window 54, beam splitter 18, and the light fiber 20 b. Thereflected light hγ_(r) is detected by the monitoring informationprocessor 28. When the monitoring information processor 28 detects theend point of damascene grooves 800, 801 shown in FIG. 14, the dry etchprocess is stopped.

In step S208, the semiconductor substrate 1 is removed from the processchamber 50 of the plasma process. Thereafter, via holes are provided inthe insulating film 400 at the bottom of the damascene grooves 800, 801and on the source/drain regions 310, 311 by a dry etching process. Then,the damascene grooves 800, 801 and the via holes are filled with copper,for example, by electroplating. After a chemical mechanicalplanarization process so as to implement damascus interconnections inthe damascene grooves 800, 801, a circuit layer is formed. Thereafter,the insulating film formation and the circuit layer formation arerepeated until the manufacturing of the semiconductor device iscompleted.

In earlier methods for manufacturing the semiconductor devices, noiseappear in the spectrum of the inspection light. Such noise disturbs theaccurate monitoring of the etch process and the deposition process.Therefore, problems such as short circuits may occur in thesemiconductor devices.

However, in the method for manufacturing the semiconductor deviceaccording to the first embodiment, the relationship between the opticaxis “A” and the polarization direction “E” is optimized as shown inFIGS. 4, 5, and 8. Therefore, such noise is eliminated in the spectrum,which allows the etch process and the deposition process to be monitoredaccurately. Further, it becomes possible to increase a yield rate in themanufacturing process for the semiconductor devise.

Second Embodiment

With reference to FIG. 15, a dry process apparatus 30 has a processchamber 40 having a bottom portion 31, a lateral portion 32 disposed onthe edge of the bottom portion 31, and a cap portion 33 disposed on thelateral portion 32.

Further, an upper electrode 45 for plasma process is disposed below thecap portion 33. The edge of the upper electrode 45 for the plasmaprocess is attached to the lateral portion 32. A space surrounded by thebottom portion 31, the lateral portion 32, and the upper electrode 45for the plasma process serves as a reaction space 66 of plasma process.A vacuum pump 36 is attached to the lateral portion 32 of the processchamber 40. A substrate holder 15 is disposed on the bottom portion 31.The substrate holder 15 serves as a lower electrode. A temperaturecontroller 35 is embedded in the substrate holder 15. An object 16 to beprocessed is disposed on the substrate holder 15.

The space surrounded by the cap portion 33, the upper electrode 45 forthe plasma process, and the lateral portion 32 comprises a gas head 65.A ceiling window 55 is provided in the cap portion 33. In a case wherethe ceiling window 55 is composed of the birefringent material,equipment similar to the direction adjuster 6 shown in FIG. 1 may beattached to the ceiling window 55.

Beneath the ceiling window 55, a monitor window 56 is provided in theupper electrode 45 for the plasma process. A gas supplier 37 is attachedto the gas head 65 through an inlet port 47. The gas supplier 37supplies the gas head 65 with a reaction gas. A plurality of gas holes71 a, 71 b, 71 c, 71 d is formed in the upper electrode 45 for theplasma process. Further, a plurality of nozzle holes 70 a, 70 b, 70 c,70 d, 70 e, 70 f, 70 g, 70 h, 70 i, 70 j, 70 k, 70 l, 70 m, 70 n, 70 o,70 p, 70 q, 70 r, 70 s, 70 t, 70 u, 70 v, 70 w, 70 x, 70 y is formed inthe monitor window 56 as shown FIGS. 15 and 16. The reaction gas issupplied to the reaction space 66 of the plasma process shown in FIG. 15from the gas head 65 via the gas holes 71 a-71 d and the nozzle holes 70a-70 y.

The substrate holder 15 serving as the lower electrode is attached to animpedance matching device 42 for RF power. A variable capacitor mayconstitute the impedance matching device 42 of the RF power. Theimpedance matching device 42 is attached to a RF power supply 43. Theimpedance matching device 42 is used for matching electrical impedancesbetween the RF power supply 43 and the substrate holder 15. On the otherhand, the upper electrode 45 for the plasma process is grounded.

Disposed above the dry process apparatus 30 are the illumination source12 and the lens 14, shown in FIG. 1. The monitoring informationprocessor 28 detects the reflected light of the inspection light hγ_(i)from the object 16.

With reference again to FIG. 15, each diameter “a” of the nozzle holes70 a-70 y formed in the monitor window 65 is smaller than a laserdiameter “d” of the inspection light hγ_(i) at the monitor window 65.For example, the laser diameter “d” is 6-7 mm, and each diameter “a” ofthe nozzle holes 70 a-70 y is 1 mm. Since the inspection light hγ_(i) isnot focused at each of the nozzle holes 70 a-70 y, the inspection lighthγ_(i) is not scattered by the nozzle holes 70 a-70 y. Therefore, thenozzle holes 70 a-70 y do not affect spectrum obtained by the monitoringinformation processor 28 shown in FIG. 1.

Such nozzle holes are not formed in a monitor window of the processmonitoring system in earlier technology. Therefore, the reaction gasconcentration beneath the monitor window becomes lower than in otherspace. Consequently, the etching rate beneath the monitor window isdecelerated and the uniformity of the surface of the substrate isdecreased. On the other hand, since the nozzle holes 70 a-70 y areformed in the monitor window 56 as shown in FIG. 16, the reaction gasconcentration beneath the monitor window 56 remains the same as otherregions. Therefore, both etching rate beneath the monitor window 56 andof other area on the surface of the object 16 are equivalent, since thenozzle holes 70 a-70 y formed in the monitor window 56 is opposed to theobject 16. Consequently, the evenness of the etching rate on the object16 is increased and the precision of the end point monitoring is alsoincreased.

An amorphous material such as glass may be used for the monitor window56 according to the second embodiment of the present invention. Also,birefringent crystals such as sapphire, quarts, and calcite areavailable for the monitor window 56.

With reference next to FIG. 17, a process monitoring method according tothe second embodiment of the present invention is described.

In step S301, the object 16 to be processed is disposed on the substrateholder 15 of the dry process apparatus 30 as shown in FIG. 15. In thiscase, the object 16 is opposed to the nozzle holes 70 a-70 y formed inthe monitor window 56.

In step S302, the inspection light hγ_(i) is emitted to the object 16from the illumination source 12. In step S303, the focus of theinspection light hγ_(i) is adjusted by the lens 14 so that the beamdiameter “d” at the monitor window 56 becomes larger than the nozzlehole diameter “a” shown in FIGS. 15 and 16.

In step S304, the detector 24 of the monitoring information processor 28detects the reflected light hγ_(r) spectrum from the object 16. Based onthe spectrum, the calculator 26 determines information on the thicknessdirection of the object 16

With reference next to FIG. 18, a method for manufacturing asemiconductor device according to the second embodiment of the presentinvention is described.

Steps S401 and S402 are similar to the steps S201 and S202 shown in FIG.10. In step S403, the semiconductor substrate 1 shown in FIG. 12 isdisposed on the substrate holder 15 in the process chamber 40 shown inFIG. 15. In this case, the semiconductor substrate 1 is opposed to thenozzle holes 70 a-70 y formed in the monitor window 56.

In step S404, the inspection light hγ_(i) propagates through the monitorwindow 56 and the insulating film 400 shown in FIG. 12 is exposed to thepolarized inspection light hγ_(i). Thereafter, the focus of theinspection light hγ_(i) is adjusted by the lens 14 so that the beamdiameter “d” at the monitor window 56 becomes larger than the nozzlehole diameter “a” shown in FIGS. 15 and 16.

In step S405, the pressure of the process chamber 40 is reduced with thevacuum pump 36. Thereafter, the reaction gas is supplied to the interiorof the process chamber 40 through the nozzle holes 70 a-70 y of themonitor window 56 and the gas holes 71 a-71 d of the upper electrode 45for the plasma process.

In step S406, the RF power is applied to the substrate holder 15.Consequently, a plasma glow discharge is generated and the insulatingfilm 400 exposed from the etch masks 900-902 shown in FIGS. 12 and 13 isselectively etched by the gas reaction.

In step S407, the reflected light hγ_(r) from the surface of theinsulating film 400 is detected by the monitoring information processor28 shown in FIG. 1. When the monitoring information processor 28 detectsthe end point of damascene grooves 800, 801 shown in FIG. 14, the dryetch process is stopped.

In step S408, the semiconductor substrate 1 is removed from the processchamber 50 of the plasma process. Thereafter, via holes are provided inthe insulating film 400 at the bottom of the damascene grooves 800, 801and on the source/drain regions 310, 311 by the dry etching process.Then, the damascene grooves 800, 801 and the via holes are filled withcopper, for example, by electroplating. After a chemical mechanicalplanarization process so as to implement damascus interconnections inthe damascene grooves 800, 801, a circuit layer is formed. Thereafter,the insulating film formation and the circuit layer formation arerepeated until the manufacturing of the semiconductor device iscompleted.

According to the process monitoring method shown in FIG. 17 and themethod for manufacturing the semiconductor device shown in FIG. 18, theinspection light hγ_(i) is not scattered by the nozzle holes 70 a-70 eshown in FIG. 15 and it is possible to supply sufficient reaction gaseven under the monitor window 56. Therefore, it is possible to maintainthe uniformity of the gas reaction on the substrate surface in the dryprocess apparatus 30.

Other Embodiments

Although the invention has been described above by reference to theembodiment of the present invention, the present invention is notlimited to the embodiment described above. Modifications and variationsof the embodiment described above will occur to those skilled in theart, in the light of the above teachings.

For example, the method for manufacturing the semiconductor according tothe embodiment is applied to manufacturing transistors as in abovedescription. Furthermore, it is possible to apply the method accordingto the embodiment to manufacturing other active components such asdiodes.

In FIG. 15, the substrate holder 15 serving as the lower electrode holdsthe object 16. However, it is also possible to apply the processmonitoring method according to the embodiment to downstream plasmaetching systems. Further, it is possible to apply the process monitoringmethod according to the embodiment to chemical etching systems usingbarrel reactors. Also, it is possible to apply dry processes other thanthe plasma process such as a gas etching, a photo-excited etching, ahigh temperature CVD, and a photo-excited CVD. Furthermore, it ispossible to apply the process monitoring method according to theembodiment to various apparatuses requiring information on a thicknessdirection of a film, such as chemical mechanical planarization systems.

As described above, the present invention includes many variations ofembodiments. Therefore, the scope of the invention is defined withreference to the following claims.

1. A process monitoring system comprising: a process chamber configuredto hold an object to be processed; an illumination source configured toemit a light to the object; a polarizer configured to polarize thelight; a monitor window having a birefringent material and provided onthe process chamber to propagate the light; direction adjustingequipment configured to adjust a relationship between a polarizationplane of the light and a direction of an optic axis of the monitorwindow; and a monitoring information processor configured to detect thelight reflected from the object.
 2. The system of claim 1, wherein thedirection adjusting equipment comprises a rotator configured to adjustan orientation of the polarizer.
 3. The system of claim 1, wherein thedirection adjusting equipment comprises a direction adjuster configuredto adjust an orientation of the monitor window.
 4. The system of claim1, wherein the direction adjusting equipment adjusts the relationshipbetween the polarization plane and the direction of the optic axis sothat the direction of the optic axis is substantially parallel with thepolarization plane of the light.
 5. The system of claim 1, wherein thedirection adjusting equipment adjusts the relationship between thepolarization plane and the direction of the optic axis so that thedirection of the optic axis is substantially parallel with aperpendicular plane that is parallel to propagation of the light and isperpendicular to the polarization plane.
 6. The system of claim 1,wherein the direction of the optic axis is substantially parallel withpropagation of the light.
 7. A process monitoring system comprising: aprocess chamber configured to hold an object to be processed; anillumination source configured to emit a light to the object; a monitorwindow provided on the process chamber to propagate the light, themonitor window having a plurality of nozzle holes, the diameter of thenozzle holes being smaller than a beam diameter of the light in themonitor window; and a monitoring information processor configured todetect the light reflected from the object.
 8. The system of claim 7,wherein the nozzle holes formed in the monitor window are opposed to theobject.
 9. A process monitoring method comprising: inserting an objectto be processed into a process chamber, the process chamber having amonitor window containing a birefringent material; irradiating a lightto the object through the monitor window; polarizing the light;adjusting a relationship between a polarization plane of the light and adirection of an optic axis of the monitor window; and detecting thelight reflected from the object.
 10. The method of claim 9, whereinadjusting the relationship makes the direction of the optic axissubstantially parallel with the polarization plane.
 11. The method ofclaim 9, wherein adjusting the relationship makes the direction of theoptic axis substantially parallel with a perpendicular plane that isparallel to propagation of the light and is perpendicular to thepolarization plane.
 12. The method of claim 9, wherein adjusting therelationship makes the direction of the optic axis substantiallyparallel with propagation of the light.
 13. A process monitoring methodcomprising: inserting an object to be processed into a process chamber,the process chamber having a monitor window; irradiating a light to theobject through the monitor window; focusing the light so that a beamdiameter of the light in the monitor window is larger than each diameterof a plurality of nozzles hole formed in the monitor window; anddetecting the light reflected from the object.
 14. The method of claim13, wherein inserting an object further comprising disposing the objectso that the object is opposed to the nozzle holes formed in the monitorwindow.
 15. A method for manufacturing a semiconductor devicecomprising: forming an insulating film above a semiconductor substrate;arranging an etching mask on the insulating film; inserting thesemiconductor substrate into a process chamber, the process chamberhaving a monitor window containing a birefringent material; irradiatinga polarized light to a surface of the semiconductor substrate throughthe monitor window; adjusting a relationship between a polarizationplane of the light and a direction of an optic axis of the monitorwindow; etching the insulating film in the process chamber; monitoringan end point of the etching by detecting the light reflected from thesemiconductor substrate having the insulating film thereabove; andstopping the etching.
 16. The method of claim 15, wherein adjusting therelationship makes the direction of the optic axis substantiallyparallel with the polarization plane.
 17. The method of claim 15,wherein adjusting the relationship makes the direction of the optic axissubstantially parallel with a perpendicular plane that is parallel topropagation of the light and is perpendicular to the polarization plane.18. The method of claim 15, wherein adjusting the relationship makes thedirection of the optic axis substantially parallel with propagation ofthe light.
 19. A method for manufacturing a semiconductor devicecomprising: forming an insulating film above a semiconductor substrate;arranging an etching mask on the insulating film; inserting thesemiconductor substrate into a process chamber, the process chamberhaving a monitor window; focusing a light so that a beam diameter of thelight in the monitor window is larger than each diameter of a pluralityof nozzle holes formed in the monitor window; supplying a reaction gasinto the process chamber through the nozzle holes; etching theinsulating film in the process chamber; monitoring an end point of theetching by detecting the light reflected from the semiconductorsubstrate having the insulating film thereabove; and stopping theetching.
 20. The method of claim 19, wherein inserting the semiconductorsubstrate further comprising disposing the semiconductor substrate sothat the semiconductor substrate is opposed to the nozzle holes formedin the monitor window.